Usb Communication Protocol Serial Bus Driver
Usb Communication Protocol Full And High

Standards such as the HID Class Specification which details the common operation of devices (keyboards, mice etc).

Some chapters were churned out by marketing, others aimed at the lower link layer.

The most important piece of information in this chapter is to make reference to the Universal Serial Bus Device Class Specifications.

Usb Communication Protocol Full And High

Introduces Low, Full and High Speed ranges with a feature list straight from marketing.

This chapter provides a basic overview of a USB system including topology, data rates, data flow types, basic electrical specs etc.

It introduces terms such as endpoints and pipes then spends most of the chapter on each of the data flow types (Control, Interrupt, Isochronous and Bulk).

While its important to know each transfer type and its properties it is a little heavy on for a first reader.

The important information here is that a type A connector is oriented facing downstream and a type B connector upstream.

Therefore it should be impossible to plug a cable into two upstream ports.

All detachable cables must be fullhigh speed, while any low speed cable must be hardwired to the appliance.

Other than a quick look at the connectors, you can skip this chapter unless you intend to manufacture USB connectors andor cables.

PCB designers can find standard footprints in this chapter.

The more important parts of this chapter are the device speed identification by using a resistor to bias either data line and bus powered devices vs self powered devices.

Good USB device datasheets will detail what value bus termination resistors you will need for bus impedance matching.

This chapter describes the USB packets at a byte level including the sync, pid, address, endpoint, CRC fields.

Once this has been grasped it moves on to the next protocol layer, USB packets.

Most developers still dont see these lower protocol layers as their USB device ICs take care of this.

However a understanding of the status reporting and handshaking is worthwhile.

This details the bus enumeration and request codes (set address, get descriptor etc) which make up the most common protocol layer USB programmers and designers will ever see.

Usb Communication Protocol Serial Bus Driver

This includes frame and microframe generation, host controller requirements, software mechanisms and the universal serial bus driver model.

Unless you are designing Hosts, you can skip this chapter.

Unless you are designing Hubs, you can skip this chapter.

So now we can begin to read the parts of the standard relevant to our needs.